Scandiobabingtonite | |
---|---|
General | |
Category | Inosilicate |
Formula (repeating unit) | Ca 2(Fe 2+, Mn)Sc Si 5 O 14(OH) |
IMA symbol | Sbab [1] |
Strunz classification | 9.DK.05 |
Crystal system | Triclinic |
Crystal class | Pinacoidal (1) (same H-M symbol) |
Space group | P1 |
Unit cell | a = 7.536 Å, b = 11.734 Å c = 6.748 Å; α=91.70° β=93.86°, γ=104.53°; Z = 2 |
Identification | |
Color | Colorless, pale grey-green |
Crystal habit | Prismatic crystals |
Cleavage | Perfect on {001} and {1-10} |
Tenacity | Brittle |
Mohs scale hardness | 6 |
Luster | Vitreous |
Diaphaneity | Transparent |
Density | 3.24 g/cm3 |
Optical properties | biaxial positive |
Refractive index | nα= 1.686 nβ= 1.694 nγ= 1.709 |
Birefringence | δ=0.023 |
Pleochroism | Strong with colors pink(γ') to green(α') |
Dispersion | r > v strong |
References | [2] [3] [4] [5] |
Scandiobabingtonite was first discovered in the Montecatini granite quarry near Baveno, Italy in a pegmatite cavity. Though found in pegmatites, the crystals of scandiobabingtonite are sub-millimeter sized, and are tabular shaped. Scandiobabingtonite was the sixth naturally occurring mineral discovered with the rare earth element scandium, and grows around babingtonite, with which it is isostructural, hence the namesake. It is also referred to as scandian babingtonite. The ideal chemical formula for scandiobabingtonite is Ca2(Fe2+,Mn)ScSi5O14(OH). [2]
Scandiobabingtonite is found in association with orthoclase, quartz, light blue albite, stilbite, fluorite, and mica. When found with these minerals, the scandiobabingtonite crystals are emplanted on the surface of the other minerals. It also occurs as growth around green-black prismatic crystals of babingtonite. The samples of scandiobabingtonite that have been discovered have shown that they start out growing from a seed of babingtonite crystal. This is how scandiobabingtonite gets its chemical structure. The starting seed of babingtonite is still present in the center of the resulting crystal and can be detected with optical and chemical studies. [2] Scandiobabingtonite is a uniquely rare mineral, as it occurs in very small amounts in few locations around the world. [4] It is one of thirteen naturally occurring minerals where scandium is a dominant member. The other scandium minerals are bazzite, cascandite, hetftetjernite, jervisite, juonniite, kolbeckite, kristiansenite, magbasite, oftedalite, pretulite, thortveitite, and titanowodginite. [3] [6] Scandium can also concentrate in other minerals, such as in ferromagnesian minerals, aluminum phosphate minerals, meteoric minerals, and other minerals containing rare earth elements, but it occurs in trace amounts. [5]
Scandiobabingtonite is a colorless or lightly gray-green colored transparent mineral with a glassy or vitreous luster. It exhibits a hardness of 6 on the Mohs hardness scale. Scandiobabingtonite occurs as short, prismatic crystals that are slightly elongated on the [001] axis which gives it a tabular or platy shape. Its crystals are characterized by the {010}, {001}, {110}, {1-10}, and {101} faces. Scandiobabingtonite is brittle and shows perfect cleavage along the {001} and {1-10} planes. The measured density is 3.24 g/cm3. [2]
Scandiobabingtonite is biaxial positive, which means it will refract light along two axes. It exhibits a 2V(measured)=64(2)°, strong dispersion with r>v, and displays strong pleochroism with colors ranging from pink (γ') to green(α'). The extinction angle along the (110) is 6°. Z:Φ=-250°, ρ=47°; Y:Φ=146°, ρ=75°; X:Φ=42°, ρ=47°. [2]
Scandiobabingtonite is isostructural with babingtonite, and has the same chemical properties as well. It is an inosilicate with 5-periodic single chains. [4] Scandium replaces the Fe 3+ in babingtonite in six-fold coordination. The empirical chemical formula for scandiobabingtonite is (Ca1.71,Na0.25)Σ0.97(Fe2+0.65,Mn0.32)Σ0.97(Sc0.91,Sn0.04,Fe3+0.03)Σ0.98Si5.09O14.00(OH)1.00. Simplified, the formula is Ca2(Fe2+,Mn)ScSi5O14(OH) [2]
Oxide | wt% | Range |
---|---|---|
SiO2 | 55.26 | 54.61-55.62 |
SnO2 | 1.21 | 1.09-1.34 |
Sc2O3 | 11.32 | 11.01-11.51 |
FeO | 8.48 | - |
Fe2O3 | 0.5 | - |
CaO | 17.33 | 17.14-17.69 |
MnO | 4.11 | 3.43-5.18 |
Na2O | 1.40 | 1.37-1.43 |
H2O | 1.63 | - |
Total | 101.24 | - |
Scandiobabingtonite is in the triclinic crystal system, with space group P1. The unit cell dimensions are a=7.536(2) Å, b=11.734(2) Å, c=6.748(2) Å, α=91.70(2)°, β=93.86(2)°, γ=104.53(2)°. These dimensions are almost identical to those of babingtonite. The difference in dimensions is caused by the replacement of iron with scandium in the Fe3+-centered octahedra. The Fe3+-O distance measures as 2.048 Å, while the Sc-O distance is 2.092 Å. This equates to a slightly larger octahedra in scandiobabingtonite than babingtonite. [2]
Vivianite (Fe2+
Fe2+
2(PO
4)
2·8H
2O) is a hydrated iron phosphate mineral found in a number of geological environments. Small amounts of manganese Mn2+, magnesium Mg2+, and calcium Ca2+ may substitute for iron Fe2+ in the structure. Pure vivianite is colorless, but the mineral oxidizes very easily, changing the color, and it is usually found as deep blue to deep bluish green prismatic to flattened crystals.
Vivianite crystals are often found inside fossil shells, such as those of bivalves and gastropods, or attached to fossil bone.
Hübnerite or hubnerite is a mineral consisting of manganese tungsten oxide (chemical formula MnWO4). It is the manganese endmember of the manganese–iron wolframite solid solution series. It forms reddish brown to black monoclinic prismatic submetallic crystals. The crystals are typically flattened and occur with fine striations. It has a high specific gravity of 7.15 and a Mohs hardness of 4.5. It is transparent to translucent with perfect cleavage. Refractive index values are nα = 2.170 - 2.200, nβ = 2.220, and nγ = 2.300 - 2.320.
Allanite (also called orthite) is a sorosilicate group of minerals within the broader epidote group that contain a significant amount of rare-earth elements. The mineral occurs mainly in metamorphosed clay-rich sediments and felsic igneous rocks. It has the general formula A2M3Si3O12[OH], where the A sites can contain large cations such as Ca2+, Sr2+, and rare-earth elements, and the M sites admit Al3+, Fe3+, Mn3+, Fe2+, or Mg2+ among others. However, a large amount of additional elements, including Th, U, Be, Zr, P, Ba, Cr and others may be present in the mineral. The International Mineralogical Association lists four minerals in the allanite group, each recognized as a unique mineral: allanite-(Ce), allanite-(La), allanite-(Nd), and allanite-(Y), depending on the dominant rare earth present: cerium, lanthanum, neodymium or yttrium.
Todorokite is a complex hydrous manganese oxide mineral with generic chemical formula (Na,Ca,K,Ba,Sr)
1-x(Mn,Mg,Al)
6O
12·3-4H
2O. It was named in 1934 for the type locality, the Todoroki mine, Hokkaido, Japan. It belongs to the prismatic class 2/m of the monoclinic crystal system, but the angle β between the a and c axes is close to 90°, making it seem orthorhombic. It is a brown to black mineral which occurs in massive or tuberose forms. It is quite soft with a Mohs hardness of 1.5, and a specific gravity of 3.49 - 3.82. It is a component of deep ocean basin manganese nodules.
Vauxite is a phosphate mineral with the chemical formula Fe2+Al2(PO4)2(OH)2·6(H2O). It belongs to the laueite – paravauxite group, paravauxite subgroup, although Mindat puts it as a member of the vantasselite Al4(PO4)3(OH)3·9H2O group. There is no similarity in structure between vauxite and paravauxite Fe2+Al2(PO4)2(OH)2·8H2O or metavauxite Fe3+Al2(PO4)2(OH)2·8H2O, even though they are closely similar chemically and all minerals occur together as secondary minerals. Vauxite was named in 1922 for George Vaux Junior (1863–1927), an American attorney and mineral collector.
Zanazziite is a complex hydrated phosphate mineral from the roscherite group. It is a magnesium beryllium phosphate mineral. Zanazziite arises as barrel-shaped crystals and can reach up to 4 mm. It grows alongside quartz minerals. It is found in the crevices of Lavra da Ilha pegmatite, near Taquaral, in northeastern Minas Gerais, Brazil. Zanazziite is named after Pier F. Zanazzi. Zanazziite has an ideal chemical formula of Ca2Mg5Be4(PO4)6(OH)4·6H2O.
Bazzite is a beryllium scandium cyclosilicate mineral with chemical formula Be3Sc2Si6O18. It crystallizes in the hexagonal crystal system typically as small blue hexagonal crystals up to 2 cm length. It has a Mohs hardness of 6.5-7 and a specific gravity of 2.77 to 2.85.
Holmquistite is a lithium magnesium aluminium inosilicate mineral with chemical formula Li2(Mg,Fe2+)3Al2Si8O22(OH)2. It crystallizes in the orthorhombic crystal system as prismatic crystals up to 10 cm (3.9 in) or as massive aggregates. It has a Mohs hardness of 5-6 and a specific gravity of 2.95 to 3.13.
Julgoldite is a member of the pumpellyite mineral series, a series of minerals characterized by the chemical bonding of silica tetrahedra with alkali and transition metal cations. Julgoldites, along with more common minerals like epidote and vesuvianite, belong to the subclass of sorosilicates, the rock-forming minerals that contain SiO4 tetrahedra that share a common oxygen to form Si2O7 ions with a charge of 6- (Deer et al., 1996). Julgoldite has been recognized for its importance in low grade metamorphism, forming under shear stress accompanied by relatively low temperatures (Coombs, 1953). Julgoldite was named in honor of Professor Julian Royce Goldsmith (1918–1999) of the University of Chicago.
Bityite is considered a rare mineral, and it is an endmember to the margarite mica sub-group found within the phyllosilicate group. The mineral was first described by Antoine François Alfred Lacroix in 1908, and later its chemical composition was concluded by Professor Hugo Strunz. Bityite has a close association with beryl, and it generally crystallizes in pseudomorphs after it, or in cavities associated with reformed beryl crystals. The mineral is considered a late-stage constituent in lithium bearing pegmatites, and has only been encountered in a few localities throughout the world. The mineral was named by Lacroix after Mt. Bity, Madagascar from where it was first discovered.
Cervandonite is a rare arsenosilicate mineral. It has a chemical formula (Ce,Nd,La)(Fe3+
,Fe2+
,Ti4+
,Al)
3SiAs(Si,As)O
13 or (Ce,Nd,La)(Fe3+
,Fe2+
,Ti,Al)
3O
2(Si
2O
7)(As3+
O
3)(OH). It has a monoclinic crustal structure with supercell (Z=6), the crystal structure was established as a trigonal subcell, with space group R3m and a = 6.508(1)Ǻ, c = 18.520(3) Ǻ, V 679.4(2) Ǻ3, and Z=3. It was first described by Buhler Armbruster in 1988, but it has proven to be problem due to the extreme scarcity of single crystals and its unusual replacement of silicon and arsenic. Cervandonite is named after the location where it was first described, Pizzo Cervandone (Scherbadung), Italy in the Central Alps.
Cleusonite is a member of the crichtonite group of minerals with the chemical formula (Pb,Sr)(U4+
,U6+
)(Fe2+
,Zn)
2(Ti,Fe2+
,Fe3+
)
18(O,OH)
38. This group of minerals contains approximately thirteen complex metal titanates. The structures of minerals of this group is complicated by frequent fine-scale twinning and metamictization due to radioactive elements. The crichtonite group consists of members of related mineral species of the type A{BC2D6E12}O38 which are characterized by their predominant cations (as seen in crichtonite (Sr), senaite (Pb), davidite (REE + U), landauite (Na), loveringite (Ca), lindsleyite (Ba), and mathiasite (K).
Cyrilovite (NaFe33+(PO4)2(OH)4·2(H2O)) is a hydrous sodium iron phosphate mineral. It is isomorphous and isostructural with wardite, the sodium aluminium counterpart.
Fluor-liddicoatite is a rare member of the tourmaline group of minerals, elbaite subgroup, and the theoretical calcium endmember of the elbaite-fluor-liddicoatite series; the pure end-member has not yet been found in nature. Fluor-liddicoatite is indistinguishable from elbaite by X-ray diffraction techniques. It forms a series with elbaite and probably also with olenite. Liddiocoatite is currently a non-approved mineral name, but Aurisicchio et al. (1999) and Breaks et al. (2008) found OH-dominant species. Formulae are
Whiteite is a rare hydrated hydroxyphosphate mineral.
Satterlyite is a hydroxyl bearing iron phosphate mineral. The mineral can be found in phosphatic shales and was first discovered in the Big Fish River area in Yukon Territory, Canada.
Dessauite-(Y) is a mineral member of the crichtonite group with the formula (Sr,Pb)(Y,U)(Ti,Fe3+
)
20O
38. It is associated with derbylite, hematite, rutile, karelianite, siderite, and calcite. Founded in the Buca della Vena Mine, Tuscany, Italy, the mineral was called dessauite in honor of professor Gabor Dessau (1907–1983).
Wöhlerite, also known as wöehlerite is a member of the amphibole supergroup, and the wöhlerite subgroup within it. It was named after German chemist Friedrich Wöhler. It was first described by Scheerer in 1843, but the crystal structure was later solved by Mellino & Merlino in 1979. Once approved, it was grandfathered by the IMA.
Rockbridgeite is an anhydrous phosphate mineral in the "Rockbridgeite" supergroup with the chemical formula Fe2+Fe3+4(PO4)3(OH)5. It was discovered at the since-shut-down Midvale Mine in Rockbridge County, Virginia, United States. The researcher who first identified it, Clifford Frondel, named it in 1949 for its region of discovery, Rockbridge County.
Greenwoodite is the second mineral discovered in the Wigwam deposit of southeastern British Columbia, Canada. It is compositionally and structurally distinct, but compositionally related to zoltaiite, the first new mineral described from this locality. The name is in honor of Hugh J. Greenwood, retired professor and former head of the Geological Sciences Department at the University of British Columbia, Vancouver, British Columbia, Canada. Grain size, polyhedral grain boundaries, and the general lack of secondary mineralization indicate that greenwoodite is part of a prograde metamorphic assemblage. The ideal chemical formula for greenwoodite is Ba2-x(V3+OH)xV9(Fe3+, Fe2+)2Si2O22.